AlertSleep Alternative: SensaCat
AlertSleep checks whether your site answers. SensaCat checks whether the things that never answer are still running.
SensaCat is the alternative if your failures are jobs that stop running rather than endpoints that stop answering. AlertSleep is a capable and cheap uptime monitor, and for uptime specifically it is priced better than we are.
AlertSleep details below come from alertsleep.com, read September 2026.
What AlertSleep does well
Five monitors free forever with no credit card, and paid plans starting around $5 a month, put it among the cheapest entries in this category. The free tier includes SSL monitoring and a public status page, which several competitors reserve for paid plans.
SMS and phone-call alerts are included rather than sold as credits, which is unusual at this price. UptimeRobot charges $3 per 10 SMS credits; Cronitor puts SMS behind the paid tier entirely.
Checks run from four or more global regions at one-minute intervals on paid plans, and the feature set covers website, API, page speed with Core Web Vitals, SSL certificates, ports and domain expiry. The site is also localised into seven languages.
The gap: everything AlertSleep does is outbound
AlertSleep's published feature list is website monitoring, API monitoring, page speed, SSL and port monitoring. All five are outbound checks: AlertSleep calls your infrastructure and reports what came back.
That model cannot see a job that did not run. Your nightly reconciliation script failing silently produces no failing endpoint, no error rate and no slow response. The server is up, the API answers, and nothing was reconciled.
Catching that requires the inverse: your job calls the monitor, and the monitor alerts on the absence of that call. There is no heartbeat or ping endpoint in AlertSleep's published feature set.
There is also no credential or API-key expiry tracking and no multi-step process correlation.
Feature and price comparison
| Feature | AlertSleep | SensaCat |
|---|---|---|
| Free tier | 5 monitors, forever, no card | $0 forever (2 monitors, 2 credentials, 1 domain) |
| Paid entry | From ~$5/mo | $24/mo Starter |
| Check interval | 1 minute (paid) | 5 minutes (Team), 15 minutes (Free/Starter) |
| Multi-region checks | Yes, 4+ regions | No, single region |
| SMS / phone alerts | Included, not credit-metered | Team plan allowance |
| Page speed / Core Web Vitals | Yes | No |
| Heartbeat / cron monitoring | Not in published feature set | Yes |
| Domain + SSL expiry | Yes | Yes, with staged reminder zones |
| Credential / API-key expiry | No | Yes |
| Multi-step business flows | No | Yes |
Who should stay on AlertSleep
Stay if uptime is the job. Five free monitors with SSL and a status page, multi-region checks and uncharged SMS is a strong package, and at around $5 a month the paid tier is cheaper than anything comparable.
Switch, or add a second tool, when you realise the outage that cost you money never showed up as an outage. A green uptime dashboard and a job that stopped running three days ago are entirely compatible states.
SensaCat alerts on absence, not just failure. Start free.